 
   :expand        if true makes the canvas take the entire window
   :engine        can be :webgl :canvas or :auto (default :auto)
+  :default       true or false to set the default canvas to this
+                 created one. defaults to true.
 
   and either:
 

  :origins       A mapping of layer names to their origin positions. Default
                 position is center. Positions can be :center :top :bottom
                 :left :right :top-left :top-right :bottom-left :bottom-right

  and either:


  "
  [opts]
  (let [{:keys [renderer canvas layer layers stage
                origins fullscreen-button default
                default-layer] :or {origins {}
                                    default true} :as world}
        (into (make opts)
              (make-stage opts))]
    ;; add the stages to the canvas
